The following material is Open Game Content from the Menace Manual SRD
Acid Resistance 10 (Ex): An acid rainer ignores the first 10 points of acid damage from any single attack.
Acid Spray (Ex): Once every 1d4 rounds, an acid rainer can spray out a cloud of caustic mist that fills a 30-foot radius spread centered on itself. Each creature within this area takes 2d6 points of acid damage, or half damage if a Reflex save succeeds (DC 10 + 1/2 the acid rainer’s Hit Dice + its Constitution modifier).
Acid Touch (Ex): An acid rainer’s tentacles are coated with a caustic secretion that deals 1d6 points of acid damage on a successful hit.
Elemental: An acid rainer has the traits and immunities common to elementals.
Improved Grab (Ex): To use this ability, the acid rainer must hit a single opponent at least one size category smaller than itself with two tentacle attacks during the same round. If it gets a hold, it automatically deals damage for two tentacle attacks (including acid) each round that the hold is maintained.
Skill Bonuses: An acid rainer gains a +8 species bonus on Hide checks and a +4 species bonus on Move Silently checks.
Acid Rainer: CR 8; Huge elemental (air); HD 8d8+40; hp 76; Mas —; Init –2; Spd 5 ft., fly 40 ft. (average); Defense 10, touch 6, flat-footed 10 (–2 size, –2 Dex, +4 natural); BAB +6; Grap +19; Atk +9 melee (1d4+5 plus 1d6 acid, tentacle); Full Atk +9 melee (1d4+5 plus 1d6 acid, 6 tentacles) or +2 ranged; FS 15 ft. by 15 ft.; Reach 20 ft. with tentacles; SQ acid resistance 10, acid spray (DC 19), acid touch, darkvision 60 ft., elemental, improved grab; AL none; SV Fort +7, Ref +4, Will +2; AP 0; Rep +0; Str 20, Dex 7, Con 20, Int 6, Wis 11, Cha 11.
Skills: Hide +6, Listen +6, Move Silently +8, Spot +6.
Feats: Power Attack.
Advancement: 9–16 HD (Huge); 17–24 HD (Gargantuan); 25–31 HD (Colossal).
Advanced Acid Rainer: CR 11; Gargantuan elemental (air); HD 20d8+140; hp 230; Mas —; Init –2; Spd 5 ft., fly 40 ft. (average); Defense 12, touch 4, flat-footed 12 (–4 size, –2 Dex, +8 natural); BAB +15; Grap +36; Atk +20 melee (1d8+9 plus 1d6 acid, tentacle); Full Atk +20 melee (1d8+9 plus 1d6 acid, 6 tentacles) or +9 ranged; FS 20 ft. by 20 ft.; Reach 25 ft. with tentacles; SQ acid resistance 10, acid spray (DC 27), acid touch, darkvision 60 ft., elemental, improved grab; AL none; SV Fort +13, Ref +12, Will +6; AP 0; Rep +0; Str 28, Dex 7, Con 24, Int 6, Wis 11, Cha 11.
Skills: Hide +11, Listen +12, Move Silently +16, Spot +12.
Feats: Combat Reflexes, Lightning Reflexes, Power Attack, Stealthy.